Hemostasis & Disorders of Hemostasis

Comments (0)

Transcript of Hemostasis & Disorders of Hemostasis

Hemostasis & Disorders of Hemostasis What is it? Hemostasis is the process by which blood is changed to a solid state. The Three Phases Are Vascular Phase Platlet Phase Coagulation Phase Cutting or damaging blood vessels leads to vascular spasm of the smooth muscle in the vessel wall. This produces a vasoconstriction which will slow or even stop blood flow. This response will last up to 30 minutes and is localized to the damaged area. Damaged endothelial cells lining the blood vessel release von Willebrand's Factor. This substance makes the surfaces of the endothelial cells "sticky". This condition may, by itself, be enough to close small blood vessels. In larger blood vessels, platelets begin to stick to the surfaces of endothelial cells. This effect is called Platelet Adhesion. Begins 30 seconds to several minutes after phases I and II have commenced.The overall process involves the formation of the insoluble protein Fibrin from the plasma protein Fibrinogen through the action of the enzyme Thrombin.Fibrin forms a network of fibers which traps blood cells and platelets forming a thrombus or clot. Clot Retraction After 2 or 3 days, the clot begins to contract. Platelets in the clot contain contractile proteins. These proteins pull the edges of the wound together and reduces the chance of further hemorrhage. This activity also assists the repair processes. Fibrinolysis Dissolution of the clot. The breakdown of the clot is due to the production of a powerful proteolytic enzyme Plasmin. Plasmin is formed through the same chemical pathway that produces thrombin. These reactions demonstrate that materials which induce clot formation (Thrombin and Factor XII) will eventually assist in the breakup of the clot. Disorders Thrombus Embolus A thrombus is a blood clot that is present inside a blood vessel or the heart that may partially or completely obstruct the flow of blood. A mass, such as an air bubble, a detached blood clot, or a foreign body, that travels through the bloodstream and lodges so as to obstruct or occlude a blood vessel.

They both have one thing in common, they are both usually blood clots; but, the thrombus is stationary such as a deep vein thrombus in the thigh or a poplitealthrombus behind the knee.An embolus is a thrombus that has moved from one place to another. PreventionsSee doctor for regular checkupsGetting up and walking after surgeriesExcersicingUse some type of blood thining medication Deficiency of platelets in the blood. This causes bleeding into the tissues, bruising, and slow blood clotting after injury Thrombocytopenia A medical condition in which the ability of the blood to clot is severely reduced, causing the sufferer to bleed severely from even a slight injury. The condition is typically caused by a hereditary lack of a coagulation factor, most often factor VIII. Hemophilia Hemostasis Video Bibliography http://www.wisegeek.com/what-is-hemostasis.htm